Various types of ion generation devices utilizing a discharge phenomenon are commercially available. These ion generation devices are generally formed with: an ion generation element for generating ions; a high voltage transformer for supplying a high voltage to the ion generation element; a high voltage generation circuit for driving the high voltage transformer; and a power supply input portion such as a connector.
As examples of the commercially available ion generation element, there can be an ion generation element in which a metal wire, a metal plate having an acute-angled portion, a needle-shaped metal or the like is used as a discharge electrode and in which a metal plate, a grid or the like of ground potential is used as an induction electrode (opposite electrode) and an ion generation element in which a metal wire, a metal plate having an acute-angled portion, a needle-shaped metal or the like is used as a discharge electrode and in which ground is used instead of an induction electrode and no induction electrode is particularly arranged. In these ion generation elements, air functions as an insulator. In these ion generation elements, when a high voltage is applied between the discharge electrode and the induction electrode or the ground, electric field concentration occurs at the acute-angled top end of the discharge electrode, air close to the top end is subjected to breakdown and thus a discharge phenomenon is obtained, with the result that ions are generated.
An example of the ion generation device having the ion generation element that generates ions in the above method is disclosed in patent document 1. The ion generation device disclosed in patent document 1 is a device that includes a discharge electrode having a needle-shaped metal and a perforated flat-plate electrode provided opposite the discharge electrode, and that takes, out of the device, positive ions and negative ions generated together with corona discharge.
Another example of the ion generation device having the ion generation element that generates ions in the above method is disclosed in patent document 2. The ion generation device disclosed in patent document 2 is a device that includes a high voltage generation circuit utilizing an alternating-current waveform in a commercial power supply.
Yet another example of the ion generation device having the ion generation element that generates ions in the above method is disclosed in patent document 3. The ion generation device disclosed in patent document 3 is a device that uses, in a high voltage generation circuit, a switching element which drives a step-up transformer and a control circuit which outputs a pulse signal for controlling the turning on and off of the switching element, and that can use, as the control circuit, a microcontroller (microcomputer).
An example of a corona discharge device that generates ozone with corona discharge is disclosed in patent document 4. The corona discharge generation device disclosed in patent document 4 is a device in which in order to generate a pulse train for generating a high voltage, with a central processing unit (CPU), pulse train modulation such as pulse width modulation (PWM) or pulse position modulation (PPM) is used.